Pacific skipjack tuna

The Science

Skipjack Tuna have a high metabolism, and can eat up to 25% of their bodyweight a day. [4] 

The Fishery

Making up at least 60% of legally caught, Skipjack is the most heavily fished tuna worldwide. [3]

The Seafood

The canned tuna market is by far the most frequent production, with over 95% of skipjack tuna contributing to canned tuna supply. [4]   

The Science

The Science
California Department of Fish and Game/ CC

Taxonomic description

  • Have a silver body, with a dark blue-black back, and four to six dark stripes along their sides [2,4]
  • Have very few scales, except for along their lateral line and head [4]
  • Mature at length of 1.3 feet, but can grow up to four feet and over 70 pounds [4,6,7]

Distribution

  • Throughout Pacific, Atlantic, and Indian Oceans in tropical and subtropical waters [1,2, 4]
  • Highly migratory [1,2,4]

Life history

  • Have a life span of 7-12 years [1]
  • Mature at around a year old and 16 inches long [1,2]
  • They spawn all year long in equatorial waters and females can lay up to two million eggs [1,2]
  • Through broadcast spawning, released eggs are fertilized and hatch one day later [7]
  • Often found in schools of thousands for hunting and reproduction [3]

Habitat

  • Live in pelagic zone, spending most of their life in the open ocean [7]
  • In schools with bigeye and yellowfin tuna [7]
  • Predators include large pelagic fishes, including billfish, larger tunas, and sharks [6,7]
  • Prey on other fish, crustaceans, mollusks, and other tunas [4,6,7]

The Fishery

The Fishery
NOAA's Fisheries Collection/ CC

Seasonal availability

  • Available year round [5]

Managing authority

  • On the West Coast, managed by NOAA Fisheries and Pacific Fishery Management Council [6, 7]
  • A highly migratory species fished by many nations,  tuna is more difficult to regulate, but Inter-American Tropical Tuna Commission (IATTC)  and the Western and Central Pacific Fisheries Commission (WCPFC) manage the fishery internationally [5]

Gear type

  • Purse seines, troll, artisanal handline, pelagic longline, pelagic hook-and-line, and pole-and-line [4,5,7] 
  • Predominantly use purse seines [5] 

Status of the fishery

  • Skipjack populations are difficult to assess due to high and variable productivity, but populations are thought to be stable and not overfished or subject to overfishing as of 2015 stock assessment [5,7]
  • Rapid growth and reproduction help tuna resist fishing pressure [7]
  • The Fishery Management Plan for U.S. West Coast fisheries for Highly Migratory Species management includes:
    • Permits and documentation of catch [5]
    • Gear constraints and requirements for operation [5]
    • Large vessels require observer coverage and other vessels are subject to observer request by NOAA [5]
  • Measures have been adopted from the WCPFC and IATTC to regulate catch of juvenile tuna effecting other species through use of purse seine [5]

Potential ecosystem impacts

  • When large purse-seine nets are set around Fish-Aggregation-Devices, there is a substantial amount of bycatch, including: other fish, sharks, rays, and sometimes even sea turtles, whales, or dolphins. [2,5,7,9]
  • Because fishing gears used for these tuna typically do not touch the ocean floor, there is minimal impact on the surrounding habitat [6,7]

The Seafood

The Seafood
Cooking with Dog- https://cookingwithdog.com/recipe/skipjack-tuna-steak/

Edible portions

  • Steaks, loins, headed and gutted, and canned [7]

Description of meat

  • Deep red when raw, light gray when cooked [5, 7]
  • Large flakes of firm, moist, mild meat [5, 7]
  • Has the most pronounced taste of tropical tunas [5, 7]

Culinary uses

  • Can be made fresh or frozen as steaks, loins, or headed and gutted [7]
  • Typically fried, broiled, or sautéed [7]
  • Most often eaten as canned, as “canned light” or “chunk light” tuna [4,7]

Nutritional information 

  • Great source of low-fat protein [7]
  • Significant levels of omega-3 that benefit health in multiple ways [1]
  • Nutrition facts given for a 100g serving [5]

Toxicity report

  • Canned light tuna has a moderate amount of mercury contamination, but is the safer choice compared to other canned tuna [8]

Seasonal availability

  • Available year round [5]

References

[1] AnimalSpot. 2018. Skipjack Tuna. Webhttp://www.animalspot.net/skipjack-tuna.html. Accessed: 31 October 2018 

 

[2] WWF. 2017. Skipjack Tuna. Web. http://wwf.panda.org/knowledge_hub/endangered_species/tuna/skipjack_tuna/. Accessed: 31 October 2018

 

[3] Oceana. Skipjack Tuna. Web.https://oceana.org/marine-life/ocean-fishes/skipjack-tuna. Accessed: 31 October 2018

 

[4] This Fish. 2013. Species: Skipjack Tuna. Web. https://thisfish.info/fishery/species/skipjack-tuna/. Accessed: 1 November 2018

 

[5] FishWatch. 2018. Pacific Skipjack Tuna. Web. https://www.fishwatch.gov/profiles/pacific-skipjack-tuna. Accessed: 1 November 2018

 

[6] NOAA Fiseries. Pacific Skipjack Tuna. Web. https://www.fisheries.noaa.gov/species/pacific-skipjack-tuna. Accessed: 1 November 2018

 

[7] FishChoice. Skipjack Tuna. Web. https://fishchoice.com/buying-guide/skipjack-tuna. Accessed: 1 November 2018 

 

[8] Environmental Defense Fund. 2018. Mercury alert: Is canned tuna safe?. Web. https://www.edf.org/oceans/mercury-alert-canned-tuna-safe . Accessed: 5 November 2018 

 

[9] GreenPeace. 2014. If You Eat Tuna, You Should Know These Five Fish. Web. https://www.greenpeace.org/usa/eat-tuna-know-fish/. Accessed: 5 November 2018